214 lines
7.0 KiB
Python
214 lines
7.0 KiB
Python
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"""
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Note: for naming purposes, most tests are title with as e.g. "test_nlargest_foo"
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but are implicitly also testing nsmallest_foo.
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"""
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from itertools import product
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import numpy as np
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import pytest
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import pandas as pd
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from pandas import Series
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import pandas._testing as tm
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main_dtypes = [
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"datetime",
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"datetimetz",
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"timedelta",
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"int8",
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"int16",
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"int32",
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"int64",
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"float32",
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"float64",
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"uint8",
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"uint16",
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"uint32",
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"uint64",
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]
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@pytest.fixture
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def s_main_dtypes():
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"""
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A DataFrame with many dtypes
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* datetime
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* datetimetz
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* timedelta
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* [u]int{8,16,32,64}
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* float{32,64}
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The columns are the name of the dtype.
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"""
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df = pd.DataFrame(
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{
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"datetime": pd.to_datetime(["2003", "2002", "2001", "2002", "2005"]),
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"datetimetz": pd.to_datetime(
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["2003", "2002", "2001", "2002", "2005"]
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).tz_localize("US/Eastern"),
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"timedelta": pd.to_timedelta(["3d", "2d", "1d", "2d", "5d"]),
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}
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)
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for dtype in [
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"int8",
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"int16",
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"int32",
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"int64",
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"float32",
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"float64",
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"uint8",
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"uint16",
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"uint32",
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"uint64",
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]:
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df[dtype] = Series([3, 2, 1, 2, 5], dtype=dtype)
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return df
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@pytest.fixture(params=main_dtypes)
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def s_main_dtypes_split(request, s_main_dtypes):
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"""Each series in s_main_dtypes."""
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return s_main_dtypes[request.param]
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def assert_check_nselect_boundary(vals, dtype, method):
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# helper function for 'test_boundary_{dtype}' tests
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ser = Series(vals, dtype=dtype)
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result = getattr(ser, method)(3)
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expected_idxr = [0, 1, 2] if method == "nsmallest" else [3, 2, 1]
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expected = ser.loc[expected_idxr]
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tm.assert_series_equal(result, expected)
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class TestSeriesNLargestNSmallest:
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@pytest.mark.parametrize(
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"r",
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[
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Series([3.0, 2, 1, 2, "5"], dtype="object"),
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Series([3.0, 2, 1, 2, 5], dtype="object"),
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# not supported on some archs
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# Series([3., 2, 1, 2, 5], dtype='complex256'),
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Series([3.0, 2, 1, 2, 5], dtype="complex128"),
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Series(list("abcde")),
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Series(list("abcde"), dtype="category"),
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],
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)
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def test_nlargest_error(self, r):
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dt = r.dtype
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msg = f"Cannot use method 'n(larg|small)est' with dtype {dt}"
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args = 2, len(r), 0, -1
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methods = r.nlargest, r.nsmallest
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for method, arg in product(methods, args):
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with pytest.raises(TypeError, match=msg):
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method(arg)
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def test_nsmallest_nlargest(self, s_main_dtypes_split):
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# float, int, datetime64 (use i8), timedelts64 (same),
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# object that are numbers, object that are strings
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ser = s_main_dtypes_split
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tm.assert_series_equal(ser.nsmallest(2), ser.iloc[[2, 1]])
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tm.assert_series_equal(ser.nsmallest(2, keep="last"), ser.iloc[[2, 3]])
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empty = ser.iloc[0:0]
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tm.assert_series_equal(ser.nsmallest(0), empty)
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tm.assert_series_equal(ser.nsmallest(-1), empty)
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tm.assert_series_equal(ser.nlargest(0), empty)
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tm.assert_series_equal(ser.nlargest(-1), empty)
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tm.assert_series_equal(ser.nsmallest(len(ser)), ser.sort_values())
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tm.assert_series_equal(ser.nsmallest(len(ser) + 1), ser.sort_values())
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tm.assert_series_equal(ser.nlargest(len(ser)), ser.iloc[[4, 0, 1, 3, 2]])
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tm.assert_series_equal(ser.nlargest(len(ser) + 1), ser.iloc[[4, 0, 1, 3, 2]])
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def test_nlargest_misc(self):
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ser = Series([3.0, np.nan, 1, 2, 5])
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tm.assert_series_equal(ser.nlargest(), ser.iloc[[4, 0, 3, 2]])
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tm.assert_series_equal(ser.nsmallest(), ser.iloc[[2, 3, 0, 4]])
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msg = 'keep must be either "first", "last"'
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with pytest.raises(ValueError, match=msg):
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ser.nsmallest(keep="invalid")
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with pytest.raises(ValueError, match=msg):
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ser.nlargest(keep="invalid")
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# GH#15297
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ser = Series([1] * 5, index=[1, 2, 3, 4, 5])
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expected_first = Series([1] * 3, index=[1, 2, 3])
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expected_last = Series([1] * 3, index=[5, 4, 3])
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result = ser.nsmallest(3)
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tm.assert_series_equal(result, expected_first)
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result = ser.nsmallest(3, keep="last")
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tm.assert_series_equal(result, expected_last)
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result = ser.nlargest(3)
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tm.assert_series_equal(result, expected_first)
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result = ser.nlargest(3, keep="last")
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tm.assert_series_equal(result, expected_last)
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@pytest.mark.parametrize("n", range(1, 5))
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def test_nlargest_n(self, n):
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# GH 13412
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ser = Series([1, 4, 3, 2], index=[0, 0, 1, 1])
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result = ser.nlargest(n)
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expected = ser.sort_values(ascending=False).head(n)
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tm.assert_series_equal(result, expected)
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result = ser.nsmallest(n)
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expected = ser.sort_values().head(n)
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tm.assert_series_equal(result, expected)
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def test_nlargest_boundary_integer(self, nselect_method, any_int_dtype):
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# GH#21426
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dtype_info = np.iinfo(any_int_dtype)
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min_val, max_val = dtype_info.min, dtype_info.max
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vals = [min_val, min_val + 1, max_val - 1, max_val]
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assert_check_nselect_boundary(vals, any_int_dtype, nselect_method)
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def test_nlargest_boundary_float(self, nselect_method, float_dtype):
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# GH#21426
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dtype_info = np.finfo(float_dtype)
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min_val, max_val = dtype_info.min, dtype_info.max
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min_2nd, max_2nd = np.nextafter([min_val, max_val], 0, dtype=float_dtype)
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vals = [min_val, min_2nd, max_2nd, max_val]
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assert_check_nselect_boundary(vals, float_dtype, nselect_method)
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@pytest.mark.parametrize("dtype", ["datetime64[ns]", "timedelta64[ns]"])
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def test_nlargest_boundary_datetimelike(self, nselect_method, dtype):
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# GH#21426
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# use int64 bounds and +1 to min_val since true minimum is NaT
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# (include min_val/NaT at end to maintain same expected_idxr)
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dtype_info = np.iinfo("int64")
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min_val, max_val = dtype_info.min, dtype_info.max
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vals = [min_val + 1, min_val + 2, max_val - 1, max_val, min_val]
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assert_check_nselect_boundary(vals, dtype, nselect_method)
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def test_nlargest_duplicate_keep_all_ties(self):
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# see GH#16818
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ser = Series([10, 9, 8, 7, 7, 7, 7, 6])
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result = ser.nlargest(4, keep="all")
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expected = Series([10, 9, 8, 7, 7, 7, 7])
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tm.assert_series_equal(result, expected)
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result = ser.nsmallest(2, keep="all")
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expected = Series([6, 7, 7, 7, 7], index=[7, 3, 4, 5, 6])
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tm.assert_series_equal(result, expected)
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@pytest.mark.parametrize(
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"data,expected", [([True, False], [True]), ([True, False, True, True], [True])]
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)
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def test_nlargest_boolean(self, data, expected):
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# GH#26154 : ensure True > False
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ser = Series(data)
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result = ser.nlargest(1)
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expected = Series(expected)
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tm.assert_series_equal(result, expected)
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